Klotho Level as a Marker of Low Bone Mineral Density in Egyptian Sickle Cell Disease Patients

Distinct role of Klotho in long bone and craniofacial bone: skeletal development, repair and regeneration

Bone defects are highly prevalent diseases caused by trauma, tumors, inflammation, congenital malformations and endocrine abnormalities. Ideally effective and side effect free approach to dealing with bone defects remains a clinical conundrum. Klotho is an important protein, which plays an essential role in regulating aging and mineral ion homeostasis. More recently, research revealed the function of Klotho in regulating skeleton development and regeneration. Klotho has been identified in mesenchymal stem cells, osteoblasts, osteocytes and osteoclasts in different skeleton regions. The specific function and regulatory mechanisms of Klotho in long bone and craniofacial bone vary due to their different embryonic development, ossification and cell types, which remain unclear and without conclusion. Moreover, studies have confirmed that Klotho is a multifunctional protein that can inhibit inflammation, resist cancer and regulate the endocrine system, which may further accentuate the potential of Klotho to be the ideal molecule in inducing bone restoration clinically. Besides, as an endogenous protein, Klotho has a promising potential for clinical therapy without side effects. In the current review, we summarized the specific function of Klotho in long bone and craniofacial skeleton from phenotype to cellular alternation and signaling pathway. Moreover, we illustrated the possible future clinical application for Klotho. Further research on Klotho might help to solve the existing clinical difficulties in bone healing and increase the life quality of patients with bone injury and the elderly.

Association between serum soluble α-klotho and bone mineral density (BMD) in middle-aged and older adults in the United States: a population-based cross-sectional study

BACKGROUND

Osteoporosis is a degenerative disease defined by low bone mineral density, has a high prevalence, and causes fractures at multiple sites throughout the body, greatly affecting the quality of patients. α-Klotho is an endocrine factor involved in the regulation of various metabolic processes in humans, and its role in bone metabolism has attracted widespread attention. The relationship between α-klotho and bone mineral density has not been uniformly recognized, and no large-scale correlation analysis has been conducted in the middle-aged and elderly population.

OBJECTIVE

To determine the relationship between α-klotho and bone mineral density in middle-aged and elderly people.

METHODS

Population data of 3120 individuals aged 40-79 years were obtained from the NHANES database for the period 2011-2016. Regression analysis was performed using a general linear model with serum α-klotho as the independent variable and total bone mineral density, thoracic bone mineral density, lumbar bone mineral density, pelvic bone mineral density, and trunk bone mineral density as the dependent variables, respectively. The generalized additive model was also used for smoothing curve fitting and threshold effect analysis.

RESULTS

Serum α-klotho was positively correlated with total bone mineral density at lg (Klotho) < 2.97 and with thoracic bone mineral density at lg (Klotho) > 2.69 (β = 0.05, p = 0.0006), and negatively correlated (β = -0.27, p = 0.0341) with lumbar bone mineral density at lg (Klotho) < 2.69. It also positively correlated with trunk bone mineral density (β = 0.027, p = 0.03657) and had no segmental effect but did not correlate with pelvic bone mineral density. The positive association of serum α-klotho with those aged 40-49 years, female, non-Hispanic White, and without hypertension was clearer. In the population with diabetes, a significantly positive association between total (β = 0.15, p = 0.01), thoracic (β = 0.23, p = 0.0404), and lumbar (β = 0.22, p = 0.0424) bone mineral density and α-klotho was observed.

CONCLUSIONS

α-Klotho has different relationships with total, thoracic, lumbar, and trunk bone mineral density. Among them, the positive correlation between α-klotho and trunk bone mineral density is more valuable for predicting osteoporosis. The significant effect of α-klotho on bone mineral density in diabetes patients suggests its potential as a predictive marker of diabetes progression.

Klotho reduces the risk of osteoporosis in postmenopausal women: a cross-sectional study of the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Osteoporosis (OP) is one of the diseases that endanger the health of the elderly population. Klotho protein is a hormone with anti-aging effects. A few studies have discussed the relationship between Klotho and OP. However, there is still a lack of research on larger populations. This study aims to evaluate the association between OP and Klotho in American postmenopausal women.

METHODS

This is a retrospective study. We searched the National Health and Nutrition Examination Survey (NHANES) database and collected data of 3 survey cycles, finally involving 871 postmenopausal women over 50 years old in the present study. All participants took dual-energy X-ray absorptiometry examination and serum Klotho testing at the time of investigation. After adjusting the possible confounding variables, a multivariate regression model was employed to estimate the relationship between OP and Klotho proteins. Besides, the P for trend and restricted cubic spline (RCS) were applied to examine the threshold effect and calculate the inflection point.

RESULTS

Factors influencing the occurrence of OP included age, ethnicity, body mass index and Klotho levels. Multivariate regression analysis indicated that the serum Klotho concentration was lower in OP patients than that in participants without OP (OR[log2Klotho] = 0.568, P = 0.027). The C-index of the prediction model built was 0.765, indicating good prediction performance. After adjusting the above-mentioned four variables, P values for trend showed significant differences between groups. RCSs revealed that when the Klotho concentration reached 824.09 pg/ml, the risk of OP decreased drastically.

CONCLUSION

Based on the analysis of the data collected from the NHANES database, we propose a correlation between Klotho and postmenopausal OP. A higher serum Klotho level is related to a lower incidence of OP. The findings of the present study can provide guidance for research on diagnosis and risk assessment of OP.

Low Turnover Renal Osteodystrophy With Abnormal Bone Quality and Vascular Calcification in Patients With Mild-to-Moderate CKD

Introduction

Limited information is available on renal osteodystrophy (ROD) and vascular calcification (VC) during early chronic kidney disease (CKD). This study was designed to evaluate ROD and VC in 32 patients with CKD stages II to IV.

Methods

Patients underwent dual-energy X-ray absorptiometry (DXA) for assessment of bone mineral density (BMD) and trabecular bone score (TBS), thoracic computed tomography for VC scoring using the Agatston method, and anterior iliac crest bone biopsy for mineralized bone histology, histomorphometry, and Fourier transform infrared spectroscopy (FTIR). Classical and novel bone markers were determined in the blood.

Results

Mean estimated glomerular filtration rate (eGFR) was 44 ± 16 ml/min per 1.73 m2. Of the patients, 84% had low bone turnover. In Whites, eGFR correlated negatively with the turnover parameter activation frequency (Ac.f) (r -0.48, P = 0.019) and with parameters of bone formation. Most patients had VC (>80%) which correlated positively with levels of phosphorus, c-terminal fibroblast growth factor-23, and activin. Aortic calcifications (ACs) correlated negatively with bone formation rate (BFR) and Ac.f (rho -0.62, -0.61, P < 0.001). TBS correlated negatively with coronary calcification (rho -0.42, P = 0.019) and AC (rho -0.57, P = 0.001). These relationships remained after adjustment of age. The mineral-to-matrix ratio, an FTIR metric reflecting bone quality, was negatively related to Ac.f and positively related to AC.

Conclusion

Low bone turnover and VC are predominant in early stages of CKD. This is the first study demonstrating mineral abnormalities indicating reduced bone quality in these stages of CKD.